Finite Element Simulation And Application In Groove Pressing Of H62Brass

Groove pressing is a new technique in severe plastic deformation, which has thecapability of severely refining grain size. In this paper, the finite element model ofgroove pressing was conducted using the ABAQUS software to investigate thedistribution of the equivalent strain. And several influence parameters such as pressingdepth of die, sample length, and sample thickness on the distribution of the equivalentstrain were studied. Groove pressing experiments were conducted according to the finiteelement model. The structure and mechanical characteristics of the sample were studied.The relationship between the distribution of the equivalent strain and the structure andmechanical characteristics of the sample was analyzed. So the deformation behavior ofH62brass during the groove pressing was discussed.The finite element simulation results show as below:1. The increasing rate of theequivalent strain is relatively constant during the groove pressing, however, theequivalent stain on the surface is higher than that of the center of the sample.2. Thedistribution of the equivalent strain is not uniform in the sample. The flat regionsaccumulate a non-negligible amount of equivalent strain during the groove pressing, butthe equivalent strain accumulated in each cycle is lower than the equivalent strainaccording to the theory calculation.3. The effect of the pressing depth of die, samplethickness, and sample length on the distribution of the equivalent strain were studied.The results show that the equivalent strain accumulation rate in the samples of groovepressing of6.5mm die pressing depth is evidently lower than that of7mm die pressingdepth; With the increasing of sample length, the accumulation rate of equivalent strainincreases and the uniformity of the equivalent strain distribution decreases. The effect ofthe sample thickness on the accumulation rate of equivalent strain on the surface ofsample can be neglected. The quivalent strain of the sample center is higher than that ofthe surface in the initial stage of groove pressing, however, as the groove pressing keepon, the higher equivalent strain switches to the sample surface.The conclusions of the experiments of groove pressing of H62brass are drawn asbelow: There is a close relationship between the microstructure and mechanical characteristics of H62brass after groove pressing and the distribution and value of theequivalent strain. With the increasing of the cycles of the groove pressing, the value ofthe microhardness increases as well as the distribution of the microhardness becomesmore inhomogeneous. The microhardness of sample on the surface is higher than that ofthe center. The evolution of microstructure during groove pressing can be divided intothree stages, depending on the value of the equivalent strain. In the first stage, when theequivalent strain is in the range of0<εeq<~0.8, the rate of grain refinement isrelatively high. In the second stage, when the equivalent strain is in the range of~0.8<εeq<~2.4, the grain refinement rate becomes smaller. In the third stage, whenthe equivalent strain is in the range ofε eq>~2.4, a great amount of deformed twincrystal can be observed. When the die pressing depth reduces from7mm to6.5mm,the cycles of the groove pressing increase. whenε eq>~2.0, the sample surface of6.5mm die pressing depth appears deformed twin crystal. With the increasing of samplelength and thickness, the groove pressing cycles decreases, and the microhardness onsample surface becomes more inhomogeneous. The increasing sample thickness alsoenhances the rate of grain refinement. Whenε eq>~1.0, The sample of5mm thicknessappears deformed twin crystal in both surface and center of the sample.